Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Mohan Z Mani

"Thank you very much for having published my article in record time.I would like to compliment you and your entire staff for your promptness, courtesy, and willingness to be customer friendly, which is quite unusual.I was given your reference by a colleague in pathology,and was able to directly phone your editorial office for clarifications.I would particularly like to thank the publication managers and the Assistant Editor who were following up my article. I would also like to thank you for adjusting the money I paid initially into payment for my modified article,and refunding the balance.
I wish all success to your journal and look forward to sending you any suitable similar article in future"

Dr Mohan Z Mani,
Professor & Head,
Department of Dermatolgy,
Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018

Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."

Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018

Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."

Dr Kalyani R
Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018

Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
As an experienced dentist and an academician, I proudly recommend this journal to the dental fraternity as a good quality open access platform for rapid communication of their cutting-edge research progress and discovery.
I wish JCDR a great success and I hope that journal will soar higher with the passing time."

Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
On Sep 2018

Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."

Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata

Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
On Aug 2018

Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".

Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
On Aug 2018

Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".

Dr. Mamta Gupta
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018

Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.

Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."

Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
On May 11,2011

Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."

Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
On April 2011

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.

Dr. Anuradha
On Jan 2020

Important Notice

Year : 2010 | Month : April | Volume : 4 | Issue : 2 | Page : 2320 - 2324 Full Version

Research Bias: A Review For Medical Students

Published: April 1, 2010 | DOI:
Krishna R*, Maithreyi R*,Surapaneni K M**

* 2nd Year Medical (II MBBS) Student, Saveetha Medical College & Hospital, Saveetha University, Saveetha Nagar, Thandalam, Chennai – 602 105, Tamilnadu, (INDIA). ** Assistant Professor, Department of Biochemistry, Saveetha Medical College & Hospital, Saveetha University, Saveetha Nagar, Thandalam, Chennai – 602 105, Tamilnadu, (INDIA).

Correspondence Address :
SURAPANENI KRISHNA MOHAN (MRSC),( FAGE)Assistant Professor,Department of Biochemistry,Saveetha Medical College& Hospital,Saveetha University, Saveetha Nagar,Thandalam, Chennai – 602 105, Tamilnadu, (INDIA).e-mail:


Bias can be defined as a systematic deviation from what would have been the most effective route to one goal because of commitment to another particular tendency or inclination, especially the one that prevents unprejudiced consideration of a question. A biased study loses validity with respect to the degree of the bias. There are two types of biases which are associated with most forms of research viz Random Bias and Systematic Bias. Random biases are those which occur due to sampling variability or measurement precision, they occur in essentially all quantitative studies and can be minimized but not avoided. Systematic biases are reproducible errors that produce a consistently false pattern of differences between the observed and the true values. Both random and systematic errors can question the validity of any research study. The most common categories of bias that can affect the validity of research include the following: Selection biases, which may result in the subjects in the sample being unrepresentative of the population of interest. Measurement biases, which include issues related to how the outcome of interest was measured. Intervention (exposure) biases, involve differences in how the treatment or intervention was carried out, or how the subjects were exposed to the factor of interest. The common methods that are used to reduce Bias in Research are – Randomization, Consecutive recruitment, Prospective versus Retrospective Studies and Blinding. Bias is a universal problem which is faced while designing the research study as well as during the execution of the designed research plan and it is well established fact that no study design is exempted from bias.

I) Definition of Bias
Bias is a form of systematic error that can affect scientific investigations and distort the measurement process. A biased study loses validity with respect to the degree of the bias. While some study designs are more prone to bias, its presence is universal (1).

II) Types of Research Studies:
Mainly research studies are of 2 types.

1. Quantitative Research
2. Qualitative Research (The “Soft” Side of Research)

1. Quantitative Research
Quantitative research is generally made using Scientific Methods which can include:
 The generation of models, theories and hypotheses
 The development of instruments and methods for measurement
 Experimental control and manipulation of variables
 Collection of empirical data
 Modeling and analysis of data
 Evaluation of results

2. Qualitative Research
Definition (Table/Fig 1)
“Qualitative research is the kind of research that generates insight and understanding rather than quantifiable measurements”.

The Salient features of Qualitative Research are as follows:

III) Study Designs
Study designs can be broadly categorized as descriptive or analytic (Table/Fig 2):

IV) Major Sources of Bias in Research Studies
It can be further categorized into
A) Types of BIAS
B) Major Categories of Research Bias

A) Types Of Bias
There are two types of biases associated with most forms of research:
1. Random Bias
2. Systematic Bias.

1. Random Bias
 Random Biases are those results which occur due to sampling variability or measurement precision.

 A key objective of qualitative research is a holistic understanding of the phenomenon.
 The idea of Qualitative Research is inherently problematical.
 There is Qualitative Data or Evidence and Quantitative Data or Evidence but Research itself is essentially neither Qualitative nor Quantitative.
Research consists of question, evidence, assessment, findings – deduction and induction.
 Research has a lot to do with reflection and conceptualizations.

 They occur in essentially all quantitative studies and can be minimized but not avoided.

2. Systematic Bias
 Systematic Biases are reproducible inaccuracies that produce a consistently false pattern of differences between the observed and the true values.

Random Vs Systematic Bias
 Both random and systematic errors can threaten the validity of any research study.
 However, random errors can be easily determined and addressed by using statistical analysis; most systematic errors or biases cannot be determined and addressed.
 This is because biases can arise from innumerable sources, including complex human factors.
 For this reason, avoidance of systematic errors or biases is the task of a proper research design.

B) Major Categories of Research Bias
There are many different types of biases which have been described in the research literature (3).
The most common categories of bias that can affect the validity of research include the following:
1. Selection biases, which may result in the subjects in the sample being unrepresentative of the population of interest.

2. Measurement biases, which include issues related to how the outcome of interest was measured.

3. Intervention (exposure) biases, which involve differences in how the treatment or intervention was carried out, or how the subjects were exposed to the factor of interest.

1. Selection Biases
 Selection biases occur when the groups to be compared are different.
 These differences may influence the outcome.
 The common types of sample (subject selection) biases include volunteer or referral bias, and non respondent bias.
 By definition, nonequivalent group designs also introduce selection bias. So it can be sub divided into two groups.

A) Volunteer or referral Bias
B) Non respondent Bias

A) Volunteer or Referral Bias
 Volunteer or referral bias occurs because people who volunteer to participate in a study (or who are referred to it) are often different than non-volunteers/non-referrals.
 This bias usually, but not always, favours the treatment group, as volunteers tend to be more motivated and concerned about their health.

B) Non Respondent Bias
 Non respondent bias occurs when those who do not respond to a survey, differ in important ways from those who respond or participate.
 This bias can work in either direction.

2. Measurement Biases
 Measurement biases involve systematic error that can occur in collecting relevant data.
 Common measurement biases include instrument bias, insensitive measure bias, expectation bias , recall or memory bias, attention bias and verification or work-up bias.
 It can be sub – divided into 6 types.

a) Instrument bias
b) Insensitive measure bias
c) Expectation bias
d) Recall or memory bias
e) Attention bias
f) Verification or work-up bias

A)Instrument Bias: Instrument bias occurs when calibration errors can lead to inaccurate measurements being recorded, e.g., an unbalanced weight scale.

B)Insensitive Measure Bias: Insensitive measure bias occurs when the measurement tool(s) which are used are not sensitive enough to detect what might be important differences in the variable of interest.

C)Expectation Bias: Expectation bias occurs in the absence of masking or blinding, when observers may err in measuring data towards the expected outcome. This bias usually favours the treatment group.

D)Recall or Memory Bias: Recall or memory bias can be a problem if outcomes which are being measured require that subjects recall past events. Often, a person recalls positive events more than negative ones. Alternatively, certain subjects may be questioned more vigorously than others, thereby improving their recollections.

E)Attention Bias: Attention bias occurs because people who are part of a study are usually aware of their involvement and as a result of the attention received, may give more favourable responses or perform better than people who are unaware of the study’s intent.

F)Verification or Work-Up Bias: Verification or work-up bias is associated mainly with test validation studies. In these cases, if the sample which is used to assess a measurement tool (e.g., diagnostic test) is restricted only to those who have the condition of factor being measured, the sensitivity of the measurement can be overestimated.

3.Intervention (Exposure) Biases
 Intervention or exposure biases generally are associated with research that compares groups.
 Common intervention biases include 6 sub types:
a) Contamination Bias
b) Co-Intervention Bias
c) Timing Bias
d) Compliance Bias
e) Withdrawal Bias
f) Proficiency Bias

a)Contamination Bias: Contamination bias occurs when members of the 'control' group inadvertently receive the treatment or are exposed to the intervention, thus potentially minimizing the difference in outcomes between the two groups.

b)Co-Intervention Bias: Co-intervention bias occurs when some subjects receive other (unaccounted for) interventions at the same time as that of the study treatment.

c)Timing Bias: Different issues related to the timing of intervention can be biased. If an intervention is provided over a long period of time, maturation alone could be the cause for improvement. If the duration of the treatment is very short, there may not have been sufficient time for a noticeable effect in the outcomes of interest.

d)Compliance Bias: Compliance bias occurs when differences in subject adherence to the planned treatment regimen or intervention affect the study outcomes.

e)Withdrawal Bias: Withdrawal bias occurs when subjects who leave the study (drop-outs) differ significantly from those that remain.

f) Proficiency Bias: Proficiency bias occurs when the interventions or treatments are not applied equally to the subjects. This may be due to skill or training differences among the personnel and/or due to differences in resources or procedures used at different sites.

V) Reduction in Bias
The common methods that are used to reduce Bias in Research are as follows.

1) Randomization
Randomization is a well-documented and powerful tool which is to reduce bias. Non random subject recruitment or group assignment may result in bias by introducing selection characteristics or unknown variables (eg, age, sex, duration and severity of disease, co morbid factors) to the study population. This bias is not always obvious, though. Randomization helps ensure that on an average and other than for the intervention or technique under study, different groups will be comparable with respect to known and unknown variables. Randomization schemes are also used in the (retrospective) review of comparative imaging sets to reduce reader-order bias. It is important to recognize, however, that because randomization relies on the averaging of sampling variation, in studies with small numbers of subjects or cases, it may not effectively reduce bias and may actually introduce bias (4) (Table/Fig 3).

2) Consecutive Recruitment
Nonconsecutive recruitment might inadvertently introduce characteristics that are not in proportion to those found in the target population (5).

3) Prospective versus Retrospective Studies
Retrospective studies are prone to various biases which can minimize the usefulness and impact of a given study. So it is important to define the study population and the methods of data collection and review for reader assessment. Prospective subject recruitment or data collection can be designed to reduce bias (6).

4) Blinding
Double blinded study is the best way to minimize the bias in research. A double blinded study refers to one in which both the investigator and the study subject are blinded to group assignment. Inappropriate blinding also leads to inaccuracy of the results (7).

Vi) Conclusions
Bias is a universal problem in designing the research study as well as the execution of the designed research plan and it is a well established fact that no study design is exempted from bias. Bias will distort data and a given study’s result will not reflect that which would be otherwise found in the target population (8).


Vi) Conclusions
Bias is a universal problem in designing the research study as well as the execution of the designed research plan and it is a well established fact that no study design is exempted from bias. Bias will distort data and a given study’s result will not reflect that which would be otherwise found in the target population (8).


Gregory T. Sica. Bias in Research Studies. Radiology. 2006; 238 (3): 780 – 89.
Bossuyt PM, Reitsma JB, Bruns DE, et al. Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. Radiology 2003; 226: 24–28.
Hartman JM, Forsen JW, Wallace MS, Neely JG. Tutorials in clinical research: Part IV: Recognizing and controlling bias. Laryngoscope. 2002; 112: 23-31.
Beam CA. Fundamental of clinical research for radiologists: statistically engineering the study for success. AJR Am J Roentgenol. 2002; 179: 47–52.
Kazerooni EA. Fundamentals of clinical research for radiologists. AJR Am J Roentgenol 2001; 177: 993–99.
Blackmore CC. The challenge of clinical radiology research. AJR Am J Roentgenol 2001; 176: 327–31.
Lijmer JG, Mol BW, Heisterkamp S, et al. Empirical evidence of design-related bias in studies of diagnostic tests. JAMA 1999; 282: 1061–66.
Blackmore CC, Black WC, Jarvik JG, Langlotz CP. A critical synopsis of the diagnostic and screening radiology outcomes literature. Acad Radiol. 1999; 6(suppl 1): S8–S18.

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